Apparatus for controlling tension in a running web



March 14, 1961 2,974,893

APPARATUS FOR CONTROLLING TENSION IN A RUNNING WEB c. AARON,

Filed NOV. 19, 1956 njwm,

INVENTOR.' CHARLES AARON am, w om ATTO RN EY United States Patent()APPARATUS FOR CONTROLLING TENSION IN A RUNNING WEB Charles Aaron, WestCaldwell, NJ., assignor to Cameron Machine Company, Brooklyn, N.Y., acorporation of New York Filed Nov. 19, 1956, Ser. No. 622,999

2 Claims. (Cl. 24275.43)

This invention relates to improved apparatus by means of which it ispossible to control very accurately the tension in a web during runningof the latter from one roll to another in processing of the web.

In the running of the web, the tension thereof is commonly imparted byimposing a braking eiect upon a pay-out roll of the web material and theweb tension is controlled by either increasing or reducing the brakingeiect. According to this invention, the pressure of compressed air whichoperates a brake, effective upon such a pay-out roll, is continuouslysubjected to very tine control in response to variations in forceapplied upon a guide roller by the tension in a web passing over saidroller.

A preferred embodiment of the invention and a second of numerouspossible variations of the invention are illustrated in the accompanyingdrawing without, however, limiting the invention to the particulararrangements disclosed in said drawing.

In the drawing:

Fig. 1 is a diagrammatic illustration of a preferred embodiment of thisinvention, and

Fig. 2 is a view showing a modification of a portion of the apparatusshown in Fig. 1.

Referring to Fig. l, a running web 10, which may be paper, sheetplastic, cloth or other web material being processed, is caused to passupwardly, onto, over and downwardly with respect to a guide roller 12.The latter, ordinarily, is located between a pay-out roll and areceiving roll, neither of which is shown although in the lower rightpart of Fig. 1, there is shown a neck or shaft 14 of a pay-out rollhaving associated therewith two oppositely working brake arms 16, 18,the operation of which controls the paying out of web material from sucha related pay-out roll.

The guide roller 12 is rotatably supported at its ends in sphericalbearings 20 and 22, the latter being rigidly supported upon a suitablebracket 24, riveted, bolted or otherwise rigidly fixed to a frame member26 of or adjacent to the machine by which the web is being processed;

, and the bearing 20 is yieldably supported by means which will permitminute vertical movement of the bearing 20 in response to variations intension of the running web 10.

The support for the bearing 20 comprises a pressure cylinder 28(sometimes referred to` herein as a tension sensing cylinder), having amounting stud 30 by means of which the cylinder 28 is supported forvertical adjustment upon a bracket 32 which is suitably fixed to amachine-frame. member 34. A pair of adjustment nuts 36, threaded on thestud 30 and co-acting with bracket 32,

permit the mentioned vertical adjustment of the position ice adjustablenut 46, threaded on said guide portion, is disposed a compression coilspring 48.

The bearing 20 rests upon the spring-seat element 44; and the adjustedpositions of nut 46 and of cylinder 28 are such that the spring 48 andliquid in the cylinder 28 and in a tension-sensing valve (hereinafterdescribed) will yieldably support lthe roller 12 in an approximately'horizontal attitude and the diaphragm 38 will be located approximatelyin the plane of its peripheral attachment to said cylinder.

The interior of the cylinder 28, above the diaphragm 38, is suitablyvented as, for example, by a port 50. The area within cylinder 28, belowthe diaphragm, serves as a hydraulic chamber 52 and is connected, in amanner now to be described, with duid-pressure instrumentalities bymeans of which the brake arms 16 and 18 are so operated as to vary theirbraking eiect upon shaft 14 and thereby control continuously the tensionin a web being drawn from a roll carried by said shaft and constrainedto rotate only as permitted by said shafts rotation. v

The principal mentioned duid-pressure instrumentalities aresubstantially similar fluid-pressure responsive pres- 'i sure-regulatingvalves 54 and 56 (valve 54 being sometimes referred to herein as atension-sensing valve and valve 56 being sometimes referred to herein asa brake supply valve), a manually adjustable pressure-regulating valve58 (sometimes referred to herein as a tensionadjusting valve), acam-actuated pressure-regulating valve 60, oppositely actingcam-actuating pressure cylinders 62 and 64, and a brake-actuatingpressure cylinder 66.

The mentioned fluid-pressure instrumentalities are inter-connected bysuitable piping, as shown in Fig. 1, between the tension-sensingcylinder 28 and the brake arms 16, 18. Also connected in the piping,where shown, are a check valve 68 permitting free flow of liquid fromvalve 54 toward cylinder 28, an adjustable throttle valve 70 controllingflow of liquid from cylinder 28 toward valve 54, and a pressure gauge72.

Connected between piston rods 74, 76 of diaphragms 78, 80 of thecylinders 62, 64 is a mounting piece 82 upon which is pivoted a cammember 84 the angularity of which is adjustable by means of an adjustingscrew 86 to permit the establishment of a desired relationship of thecam members cam surface 88 with reference to a plunger 90 which isoperated by said cam member to control the valve 60. A spring 92,compressed between the extremities of brake arms 16 and 18, tends tourge said arms apart to reduce the braking etect on pay-out roll shaft14 while the pressure cylinder 66 tends to draw sid arms toward eachother to increase the braking e ect.

In the described apparatus, la substantially closed or conned body ofoil or other suitable liquid completely occupies chamber 52 of thetension-sensing cylinder 28, an upper or hydraulic chamber 94 of valve54 and the piping and valves connected between said two chambers. Allother illustrated piping and pressure chambers are occupied and/ oroperated by air which, in a compressed state, enters the piping from asuitable source of supply where indicated by a legend to that effect inthe drawing.

The several illustrated pressure-regulating valves, per se, are not thepresent invention; hence, they have been shown only diagrammatically.They should have characteristics now to be given. Each should have,respectively, line pressure chambers 54LP, 56LP, 58LP and 60LP,co'nnected to the supply of compressed air to receive that air at supplypressure, regulated-pressure chambers 54RP, 56RP, SSRP and 66RP, fromwhich regulated pressure may pass to function as hereinafter described,and suitable internal valve elements, diaphragme and exhaust PatentedMar. 14, 1961v Vapart from the disclosed apparatus.

3 permittngpres'sure regulation in a well understood manner.

In valves 54 and 56, control of pressure regulation is Y,effected by.changes lin fluid pressure in chambers 94 and 496, respectively, ofsaidvalves. In valve 58, control-of pressure regulation .is "effected Vbymanipulation of `Vpres- ;sure-control Vscrew -98 and intvalve 60,controlof pres- 4:sureregulation. isV elected by longitudinal movementof lplunser 1 Y l broadly considered,'maintenance of a desired tensioninthe running web depends upon counter-acting `pressures,introduced intocylinders 62 .and 64 vthrough `valves 54`and 58. Variations in suchcounter-acting pressures govern the movement off the plunger 9G andkthereby V causevalves 56 `and 60 to control the brake arms 16 and i18Yand thereby'control the web tension. Thus, it is im- 'Aportant toconsider-thel means by which such counterlacting pressures arecontinuously controlled and; if necessary, varied to achieve correctionof variations in -the web tension. Y Suchcounter-acting pressures Yarecontrolled, on the Vone hand, by movement ofrliquid Vor shifting (ofliquid pressure into and from chamber 94 of valve 54 as diaphragm 38 ofcylinder 28 rises and falls minutely with .variations in the downwardforce imposed upon roller 12 .by variations in the tension of therunning web it). The

.increase'of the liquid Volume or pressure in chamber 294 increases the`air pressure against diaphragm 78 and Vlettwardly. On the other hand,screw98 of valve 58 constitutes manual means Vfor similarly controllingAair :pressure in cylinder 64 to control movement of the cam841leftwardly. v

Y From experience, it maybe ascertained'tha by manual adjustmentof-screw98 to establish a given air pressure Aagainst diaphragm 80(indicated on gauge 72), the differential between that pressure and thepressure applied l.oppositely against diaphragm 78 under the control ofdiaphragm'SS'wilL'if unvaried, hold the cam'84 in such l-position as tocause valves vStaud 6@ to keep steady the braking elect of brake armsY16^and 18 and thereby maintainthe desired Web tension. It is important,however, to :provide for lpractically instantaneous compensation for webtension changes that occur from conditions arising The disclosedapparatus accomplishes such compensation.

Thus, let it be supposed that the web 10 is running and that screw 98'has been set to yield the desired web tension, and that'an'undesiredincrease or decrease or alternate increases and decreases occur in theweb tension. tlf :the'variation is a tension increase, the resultantincreased downward force upon roller 12 causes diaphragm 38 to rrloveminutely downwardly, thereby forcing additional liquid to move intochamber 94. This causes valve S4 to establish an increased pressure inchamber 54RP and against diaphragm78, thereby shifting cam 84 rightward-Yly to permit plunger 9i) to rise to decrease the air pressure-inchamber 60RP of'valve 6i) and chamber 96 of valve S6. The decreasedpressure in chamber 96 causes a decrease of 'the air pressure in chamber56RP of valve 56 and in brake cylinder 66, thereby enabling spring 92'to reduce the braking effect of brake arms 16 and 18 to -providecompensatory reduction in the tension of the Arunning web.

In the event of an undesired decrease in the web tenvfsion, thediaphragm 3'8 will rise, thereby causing operations opposite tothosejust described with reference to rundesired tension increases. Thedescribed apparatus is very'eiective for giving quick compensation byminute rising and/or falling of the diaphragm 38 with conse- 'quenttension-controlling voperations as just described.

The modification of Fig. 2 is an arrangement in which thetension-adjusting valve 5S may be located at a considerable distancefrom the other disclosed apparatus if desired, When that is Adesired,-the regulated pressure, in chamber SRP, instead of being applieddirectly to dia- -pl'iragn StL-'as infFi'g. 1, tis communicated toapressurecontrol chamber 10i) of'a pressure-regulating valve 162 whichmaybe similar to valves 54 and 56. The valve v102 yhas alinepressure-chamber 1021,13 receiving air ranged to control directly theoperation of brakecylinder 66, but the inclusion of valve`56 usuallyyields more satisfactory results, y K

It will readilybe perceived that the inventive concept may -be utilizedin various other Ways Without, however, departing from the invention asset'forth in the following claims.

I claim:

l. In running-web, tension-controlling apparatus having an elongateguidemember against which a running web'presses when theweb isnndertension and which guide member is-movable in response to variationsinthe pressure'of the Web thereagainst, ya uid-pressure-operated brakemechanism adapted to vary' the tension in a running web, and aHuid-pressure circuit adapted to supply uid under pressure to said brakemechanism to control the operation of the latter; means forcontrollingthe duid pressure in said circuit, comprising mounting means,pivotally supporting one endof said guide member, a iluidpressurecylinder having a diaphragm` therein, a stem con- Ynected between theother end of said guide member and said diaphragm to actuate the latterin response to lmovement of the guide members said other end, afluid-pressure-responsive control valve connected in controllingrelation to said circuit, and a substantially closed body of lReferencesCited in the tile of this patent vUNITED STATES PATENTS y 954,089 f GossApr. 5, 1910 1,652,299 Carpenter Dec. V13, 1927 2,291,033 VGoepfrichJuly 28,1942 2,472,548 Schnell June 7, 1949 2,661,773 Kretzschmar Dec.S, A1953 2,667,887 Holacker Feb. .2, 1954 FOREIGN PATENTS 607,790Great-Britain i sept. e, i948

